Joomla FIX - content page links showing up blank

I have a Joomla site that we recently updated from 1.5.08 to 1.5.12. After the update we have run into a problem with some of the pages that we cannot figure out. 1. If we assign an article to the home page, we get a white blank page. 2. All menu link to content items show a blank page. 3. One 3rd party component (rokdownloads) also appears blank. *All other component links work perfectly. We have attempted to turn off the SEF, edit the htaccess file, etc. We need to get this resolved in the next 1 - 2 days at most. Contact me with questions.